4.0.9 - 503 Errors?

I am not sure if this is the right place to put this - but I run a decently sized forum and when I upgraded to 4.0.9 I was getting complaints of intermittent 503 errors. I rolled back to 4.0.6 and the issue has disappeared.

So which logs would you like to see? It would be good to know so that in the future when the 503 errors happen not only can we check the logs to see ourselves we know what to send over to you so that you can look into it+fix the issue in future releases.

We just upgraded our forum software and started getting 503 errors almost immediately. We are running 4.0.9 LSWS. I disabled mod_security to see if the problem goes away, but I am not seeing anything in the logs to indicate that it's a mod_security issue.

Edit: With mod_security disabled the problem persists. I just downgraded to 4.0.6 to see if it fixes this problem. I can tell you that 4.0.6 is still generating apache default pages when certain text is entered into a php input field.

We have uploaded a new 4.0.10 build, it should be the final build.
Have been tested on a few busy site that experience 503 errors, the latest build is very stable. So, all user who have manually upgrade to 4.0.10 release should download again and do a manual upgrade again.